Fluid actuated or operated nuts heretofore proposed are typified by U.S. Pat. Nos. 2,571,265, to Leufven 2,626,543, Danly, 3,154,006, Novak and 3,464,044, Rossman et al. In all of these patents, a tensile or compressive force is applied by fluid pressure, with the difference that in Leufven and Novak the force, once applied, is transferred to a nut or shim before the fluid pressure is released, while in Danly and Rossman the force is both applied and maintained by fluid pressure and released by discharging the fluid responsible for the pressure. As opposed, in Leufven and Novak relief of the tension on the bolt is achieved by applying fluid pressure to increase that tension and thereby free or loosen for removal the nut in Leufven and shim in Novak.
The concern of the present invention is an improved fluid actuated nut which depends on a spring force for maintaining a bolt under tension and utilizes fluid pressure for compressing and inactivating the spring to facilitate both tightening and removal.